Daily Archives: April 27, 2019

The so-called “Big Five” personality traits are often misunderstood. They all have catchy names, expressed by the acronym CANOE (or OCEAN), but in fact all they are is a summary of answers to certain kinds of personality questions:

Conscientiousness: I pay attention to details; I follow a schedule; …

Agreeableness: I am interested in people; I feel the emotions of others; …

Neuroticism: I get upset easily; I worry about things; …

Openness to experience: I am full of ideas; I am interested in abstractions; …

Extraversion: I am the life of the party; I start conversations; … (this last one is also measured by the MBTI test)

These tests work in multiple cultures. In this article, I am using data from the Dutch version of the test, the “Vijf PersoonlijkheidsFactoren Test” developed by Elshout and Akkerman. Specifically, I am using data from 8,954 psychology freshmen at the University of Amsterdam during 1982–2007 (Smits, I.A.M., Dolan, C.V., Vorst, H.C., Wicherts, J.M. and Timmerman, M.E., 2013. Data from ‘Cohort Differences in Big Five Personality Factors Over a Period of 25 Years’. Journal of Open Psychology Data, 1(1), p.e2). In my analysis, I have compensated for missing data and for the fact that the sample was 69% female.

The Dutch test consists of 70 items, in 5 groups of 14. The following tree diagram (click to zoom) is the result of UPGMA hierarchical clustering on pairwise correlations between all 70 items. It can be seen that they naturally cluster into 5 groups corresponding almost perfectly to the “Big Five” personality traits – the exception being item A11, which fits extraversion slightly better (r = 0.420) than its own cluster of agreeableness (r = 0.406). This lends support to the idea that the test is measuring five independent things, and that these five things are real.

On tests like this, women consistently score, on average, a little higher than men in conscientiousness, agreeableness, neuroticism, and extraversion (and in this dataset, on average, a little lower in openness to experience). Mean values for conscientiousness in this dataset (on a scale of 14 to 98) were 60.3 for women and 56.1 for men (a difference of 4.2). For agreeableness, they were 70.6 for women and 67.6 for men (a difference of 3.0). There are also small age effects for conscientiousness, agreeableness, and openness to experience (over the 18–25 age range), which I have ignored.

The chart below (click to zoom) shows distributions of conscientiousness and agreeableness among men and women, and the relative frequency of different score ranges (compensating for the fact that the sample was 69% female). Thus, based on this data, a random sample of people with both scores in the range 81 to 90 would be 74% female. With both scores in the range 41 to 50, the sample would be 72% male. This reflects a simple mathematical truth – small differences in group means can produce substantial differences at the tails of the distribution.